The widespread recognition of the use of radiation to kill or neutralize unwanted cell growth such as cancer has led to increasing interest in various types of radionuclides. In particular, Cs-131 has been identified as a radionuclide that is ideally suited for use in brachytherapy (cancer treatment using interstitial implants, i.e. "radioactive seeds"). The short half-life makes the seed effective against faster growing tumors such as those found in the brain, lung, prostate, and other sites.
Cesium-131 is produced by radioactive decay from neutron irradiated naturally occurring Ba-130 (natural Ba comprises about 0.1% Ba-130) or from enriched Ba containing additional Ba-130, which captures a neutron, becoming Ba-131. Ba-131 decays with an 11.5 day half-life to Cs-131, which decays with a 9.7 day half-life to stable Xenon-130.
In order to be effective, the Cs-131 must be exceptionally pure, i.e., free from other metals and radioactive ions including Ba-130 and Ba-131.
Harper et al., in Proc. Intern. Conf. Peaceful Uses At. Energy, 2.sup.nd, Geneva:417-22 (1958) described a distillation of Cs-131 from irradiated barium at 850.degree. C.
Buchanan et al., ORNL-IIC-10(1):298-314 (1968) described a recovery of Cs-131 by passing an acid solution of neutron irradiated barium carbonate through an ion exchange column containing a mixture of ammonium molybdophosphate (AMP) and acid washed asbestos. Cesium absorbed on the AMP and barium and other impurities passed through the column. After rinsing the column with dilute acid, then water, the AMP was dissolved and separated from the asbestos by passing a LiOH solution through the column. Cesium remained on the asbestos. After rinsing LiOH from the asbestos with water, Cs-131 was eluted with dilute acid.
Finkle et al., Nuclear Energy Ser., Div. IV, 9, Book 3:1654-56 (1951) in Finston et al., NAS-NS 3035: 56-57 (1961) described a preparation of Cs-131 by preparing a clean Ba source, dissolving BaCl.sub.2 in H.sub.2 O, re-precipitating BaCl.sub.2 .multidot.H.sub.2 O with HCl, boil supernatant solution to dryness, dissolve in H.sub.2 O and scavenge twice with 5 mg La(OH).sub.3, evaporate tracer solution to dryness several times with aqua regia to remove ammonium salts, leaving solid-free 10.2 d Cs-131 activity. Reported overall yields were about 30%.
Shabana et al., J. Radioanal. Chem. 43:21-29 (1978) reported the absorption of Na, Cs, and Ba on Dowex 1X8 resin from solutions comprising various concentrations of HCl and HNO.sub.3 and water-miscible organic solvents including methanol, ethanol, isopropanol, acetone, and dioxan.
Kubica et al., J. Radioanal. Nucl. Chem. Lett. 213(6):411-18 (1996) reported the sorption of Fr, Ra, Cs, and Ba on nickel hexacyanoferrate (II) composite ion exchanger from HCl solutions as a function of concentration and from EDTA solutions as a function of hydrogen ions concentration.
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